U.S. patent number 9,490,741 [Application Number 14/343,088] was granted by the patent office on 2016-11-08 for motor control device.
This patent grant is currently assigned to Hitachi Automotive Systems, Ltd.. The grantee listed for this patent is Hirokazu Matsui, Hiroyuki Yamada. Invention is credited to Hirokazu Matsui, Hiroyuki Yamada.
United States Patent |
9,490,741 |
Matsui , et al. |
November 8, 2016 |
Motor control device
Abstract
A motor control device according to the invention includes: a
mode setting section that sets one of a first mode in which a
charge/discharge current of a secondary battery varies according to
load fluctuation of a motor and a second mode in which the
charge/discharge current of the secondary battery becomes constant
for a predetermined time regardless of the load fluctuation of the
motor; and a drive signal generating section that generates a drive
signal for driving the motor on the basis of the mode that is set
by the mode setting section, a torque command value, and a motor
rotation speed.
Inventors: |
Matsui; Hirokazu (Hatachinaka,
JP), Yamada; Hiroyuki (Hitachinaka, JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
Matsui; Hirokazu
Yamada; Hiroyuki |
Hatachinaka
Hitachinaka |
N/A
N/A |
JP
JP |
|
|
Assignee: |
Hitachi Automotive Systems,
Ltd. (Hitachinaka-shi, JP)
|
Family
ID: |
47994948 |
Appl.
No.: |
14/343,088 |
Filed: |
July 25, 2012 |
PCT
Filed: |
July 25, 2012 |
PCT No.: |
PCT/JP2012/068851 |
371(c)(1),(2),(4) Date: |
March 06, 2014 |
PCT
Pub. No.: |
WO2013/046893 |
PCT
Pub. Date: |
April 04, 2013 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20140217935 A1 |
Aug 7, 2014 |
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Foreign Application Priority Data
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Sep 26, 2011 [JP] |
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2011-209814 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01M
10/441 (20130101); B60L 3/12 (20130101); B60L
7/14 (20130101); B60L 15/20 (20130101); H02P
27/06 (20130101); B60L 58/18 (20190201); B60L
15/2045 (20130101); B60L 3/0046 (20130101); B60L
50/51 (20190201); B60L 50/40 (20190201); B60L
58/12 (20190201); B60L 58/10 (20190201); G01R
31/007 (20130101); B60L 2240/14 (20130101); B60L
2240/545 (20130101); Y02T 10/72 (20130101); B60L
2240/12 (20130101); Y02T 10/70 (20130101); G01R
31/3835 (20190101); B60L 2240/549 (20130101); B60L
2240/642 (20130101); Y02T 10/64 (20130101); B60L
2240/425 (20130101); Y02T 90/16 (20130101); B60L
2250/26 (20130101); H01M 10/482 (20130101); Y02E
60/10 (20130101); B60L 2240/421 (20130101); B60L
2240/423 (20130101); B60L 2240/427 (20130101); B60L
2240/547 (20130101); B60L 2260/26 (20130101); B60L
2240/429 (20130101) |
Current International
Class: |
B60W
10/26 (20060101); H01M 10/44 (20060101); H02P
27/06 (20060101); B60L 3/00 (20060101); B60L
3/12 (20060101); B60L 7/14 (20060101); B60L
15/20 (20060101); B60L 11/00 (20060101); B60L
11/18 (20060101); B60W 20/00 (20160101); H01M
10/48 (20060101); G01R 31/36 (20060101); G01R
31/00 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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6-62503 |
|
Mar 1994 |
|
JP |
|
2004-7978 |
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Jan 2004 |
|
JP |
|
2008-276970 |
|
Nov 2008 |
|
JP |
|
2009-208512 |
|
Sep 2009 |
|
JP |
|
2011-97729 |
|
May 2011 |
|
JP |
|
2011097729 |
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May 2011 |
|
JP |
|
Other References
Corresponding International Search Report with English Translation
dated Oct. 30, 2012 (four (4) pages). cited by applicant.
|
Primary Examiner: Santana; Eduardo Colon
Assistant Examiner: Cook; Cortez
Attorney, Agent or Firm: Crowell & Moring LLP
Claims
The invention claimed is:
1. A motor control device comprising: a mode setting section that
sets one of a first mode in which a charge/discharge current of a
secondary battery is changed according to a load fluctuation of a
motor and a second mode in which the charge/discharge current of
the secondary battery is set as a target battery current value
configured to maintain the charge/discharge current of the
secondary battery constant within a predetermined adjustable range
regardless of the load fluctuation of the motor; and a drive signal
generating section that generates a first current command signal
configured to charge the charge/discharge current of the secondary
battery according to a load fluctuation of the motor when the first
mode is set by the mode setting section and generates a second
current command signal configured to maintain the charge/discharge
current of the secondary battery constant as the target battery
current value when the second mode is set by the mode setting
section, wherein the mode setting section sets one of the first
mode and the second mode based on a signal from an external
controller, the mode setting section sets the second mode during a
high-speed cruise travel in which torque fluctuation of the motor
is relatively small, the drive signal generating section comprises:
a first current command calculating section that outputs the first
current command signal on the basis of an inter-terminal voltage of
the secondary battery, a torque command value for driving the
motor, and a motor rotation speed; a second current command
calculating section that outputs the second current command signal
on the basis of an inter-terminal voltage of the secondary battery,
the torque command value for driving the motor, the motor rotation
speed, and the target battery current value, and a current command
switching section that selects and outputs one of the first current
command signal and the second current command signal; and the motor
is driven on the basis of a current command signal that is output
from the current command switching section.
2. The motor control device according to claim 1, wherein the mode
setting section sets the second mode during a hill-hold travel in
which torque fluctuation of the motor is relatively small.
3. The motor control device according to claim 1, wherein the mode
setting section sets the second mode during a hill-climb travel in
which torque of the motor acts only in a discharging direction.
4. The motor control device according to claim 1, wherein the mode
setting section sets the second mode during a downhill travel in
which torque of the motor acts only in a charging direction.
5. The motor control device according claim 1, wherein the mode
setting section sets the second mode during a reverse travel in
which torque fluctuation of the motor is relatively small.
6. An electric drive control apparatus for a vehicle comprising:
the motor control device according to claim 1; a secondary battery
voltage measuring section that measures inter-terminal voltage
(CCV) of the secondary battery when the motor is driven in the
second mode; and an SOC calculating section that calculates OCV of
the secondary battery based on the inter-terminal voltage (CCV) of
the secondary battery measured by the secondary battery voltage
measuring section.
7. A control apparatus for a vehicle comprising: the motor control
device according to claim 1; a secondary battery voltage measuring
section that measures inter-terminal voltage (CCV) of the secondary
battery when the motor is driven in the second mode; an SOC
calculating section that calculates OCV of the secondary battery
based on the inter-terminal voltage (CCV) of the secondary battery
measured by the secondary battery voltage measuring section; a
first determining section that determines one of hill-hold,
hill-climb, high-speed cruise, and reverse travels; and a command
section that commands the motor control device to set the second
mode when the determining section determines one of the hill-hold,
hill-climb, high-speed cruise, and reverse travels.
8. The motor control device according to claim 7, wherein the mode
setting section comprises: a first table section that derives a
minimum battery current value defined based on a torque command
value and a motor rotation speed; a second table section that
derives a maximum battery current value defined based on the torque
command value and the motor rotation speed; and a second
determining section that determines whether the target battery
current value is within a motor control range when the target
battery current value is equal to the minimum battery current value
or larger and is equal to the maximum battery current value or
smaller, and when the determination by the second determining
section is affirmative, the second mode is set by the mode setting
section.
Description
TECHNICAL FIELD
The present invention relates to a motor control device.
BACKGROUND ART
In general, multiple electric motors are mounted in an electric
drive vehicle such as a hybrid electric vehicle (HEV) and an
electric vehicle (EV), and particularly, a high-power electric
motor is used as a driving force. As a power source that supplies
power to the electric motor used as the driving force, a battery
that is formed of a battery pack including plural secondary battery
cells such as nickel hydrate battery cells or lithium battery cells
is used. A State of Charge (SOC) is used as a parameter that
indicates a charging state of the battery. For estimating the SOC
during traveling of a vehicle, in general, a method is widely used
in which open circuit voltage OCV is calculated from closed circuit
voltage CCV during traveling of the vehicle, polarization voltage,
internal resistance, and a battery current integrated value and in
which the SOC is estimated from the thus-calculated OCV.
The CCV of the each secondary battery that constitutes the battery
pack is measured for measurement of the CCV during traveling of the
vehicle, the OCV and the SOC of the each secondary battery are then
calculated from the measured values, and the SOC of the battery as
a whole is further calculated. However, because charging and
discharging are frequently repeated during traveling of the
vehicle, it is difficult to detect the CCVs of all the secondary
battery cells in an identical condition, and an error occurs to a
certain extent in detection of the CCV of the each secondary
battery cell. The error in the detection of battery voltage values
of these secondary battery cells is accumulated, an error is also
produced in the calculated SOC of the battery with respect to the
actual SOC, and this error is gradually accumulated. Considering
the above, a method of accurately calculating the SOC by measuring
the CCV in a state where the battery is driven with a constant
current has been suggested (see PTL 1).
However, a power source system that is described in PTL 1 and used
to supply power to the electric motor includes plural batteries and
plural converters, controls the plural converters to charge or
discharge some of the plural batteries with the constant current,
and charges and discharges the rest of the batteries in response to
a power request by a driving force generating section, and in the
meantime, a battery controller estimates the SOC of the battery on
the basis of the voltage of the battery during charging or
discharging with the constant current.
CITATION LIST
Patent Literature
PTL 1: JP-A-2008-276970
SUMMARY OF INVENTION
Technical Problem
In the conventional motor control device, in order to accurately
calculate the SOC of the host battery, an additional battery has to
be used to drive with a constant current the host battery that
drives the electric motor for driving the HEV or the EV and whose
SOC is subjected to measurement. This increases the number of the
batteries, thereby increasing cost.
Solution to Problem
According to a first aspect of the invention, a motor control
device includes: a mode setting section that sets one of a first
mode in which a charge/discharge current of a secondary battery is
changed according to load fluctuation of a motor and a second mode
in which the charge/discharge current of the secondary battery
becomes constant for a predetermined time regardless of the load
fluctuation of the motor; and a drive signal generating section
that generates a drive signal for driving the motor based on the
mode that is set by the mode setting section, a torque command
value, and a motor rotation speed.
According to a second aspect of the invention, in the motor control
device of the first aspect, it is preferable that the mode setting
section sets one of the first mode and the second mode based on a
signal from an external controller.
According to a third aspect of the invention, in the motor control
device of the second aspect, it is preferable that the mode setting
section sets the second mode during a hill-hold travel in which
torque fluctuation of the motor is relatively small.
According to a fourth aspect of the invention, in the motor control
device of the second aspect, it is preferable that the mode setting
section sets the second mode during a hill-climb travel in which
the torque of the motor acts only in a discharging direction.
According to a fifth aspect of the invention, in the motor control
device of the second aspect, it is preferable that the mode setting
section sets the second mode during a downhill travel in which the
torque of the motor acts only in a charging direction.
According to a sixth aspect of the invention, in the motor control
device of the second aspect, it is preferable that the mode setting
section sets the second mode during a high-speed cruise travel in
which the torque fluctuation of the motor is relatively small.
According to a seventh aspect of the invention, in the motor
control device of the second aspect, it is preferable that the mode
setting section sets the second mode during a reverse travel in
which the torque fluctuation of the motor is relatively small.
According to an eighth aspect of the invention, an electric drive
control apparatus for a vehicle includes: the motor control device
of the first aspect; a secondary battery voltage measuring section
that measures inter-terminal voltage (CCV) of the secondary battery
when the motor is driven in the second mode; and an SOC calculating
section that calculates OCV of the secondary battery based on the
inter-terminal voltage (CCV) of the secondary battery measured by
the secondary battery voltage measuring section.
According to a ninth aspect of the invention, a control apparatus
for a vehicle includes: the motor control device of the first
aspect; the secondary battery voltage measuring section that
measures inter-terminal voltage (CCV) of the secondary battery when
the motor is driven in the second mode; the SOC calculating section
that calculates the OCV of the secondary battery based on the
inter-terminal voltage (CCV) of the secondary battery measured by
the secondary battery voltage measuring section; a determining
section that determines one of the hill-hold, hill-climb,
high-speed cruise, and reverse travels; and a command section that
commands the motor control device to set the second mode when the
determining section determines one of the hill-hold, hill-climb,
high-speed cruise, and reverse travels.
Advantageous Effects of Invention
In the motor control device according to the invention, it is
possible to use only one battery for the constant current drive of
the battery in order to measure the CCV of the secondary battery
cell, to compute the OCV on the basis of the accurate CCV
measurement, and to calculate the SOC further accurately. Due to
the above, the structure as well as control of the battery is
simplified, and the battery cost can be reduced.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a schematic diagram for illustrating an overall structure
of an electric drive apparatus that includes an embodiment of a
motor control device according to the invention.
FIG. 2 is a block diagram for showing a structure of a motor drive
unit 102 in the electric drive apparatus that is shown in FIG.
1.
FIG. 3 is tables for explaining data used by a current command
determining section in the embodiment of the motor control device
according to the invention. Tables 301, 302 respectively indicate
lower limits and upper limits of an effective AC current for the
motor control that are calculated in a second current command
determining section, and tables 303, 304 indicate an effective DC
current for a battery that respectively correspond to the tables
301, 302.
FIG. 4 shows processing of the table data shown in FIG. 3 by a
current command calculating section in the motor control of the
embodiment of the motor control device according to the
invention.
FIG. 5 is a flowchart for explaining a process of shifting to a
battery constant current mode in the embodiment of the motor
control device according to the invention.
FIG. 6 is a flowchart for explaining the content of battery
constant current operation range determination processing in the
embodiment of the motor control device according to the
invention.
FIG. 7 is a flowchart for explaining a first example of battery
constant current operation permission for which the motor control
device of the embodiment according to the invention can be
used.
FIG. 8 is a flowchart for explaining a second example of the
battery constant current operation permission for which the motor
control device of the embodiment according to the invention can be
used.
FIG. 9 is a flowchart for explaining a third example of the battery
constant current operation permission for which the motor control
device of the embodiment according to the invention can be
used.
FIG. 10 is a flowchart for explaining a fourth example of the
battery constant current operation permission for which the motor
control device of the embodiment according to the invention can be
used.
FIG. 11 is a flowchart for explaining a fifth example of the
battery constant current operation permission for which the motor
control device of the embodiment according to the invention can be
used.
FIG. 12 is a flowchart for explaining a sixth example of the
battery constant current operation permission for which the motor
control device of the embodiment according to the invention can be
used.
FIG. 13 is a graph for explaining normal motor drive operation.
FIG. 14 is a diagram for explaining constant current drive
operation of a motor by using the motor control device according to
the invention.
FIG. 15 is a flowchart for explaining SOC computing processing that
is executed by a battery controller 106 in the electric drive
apparatus for a vehicle that includes the embodiment of the motor
control device according to the invention.
DESCRIPTION OF EMBODIMENTS
A description will hereinafter be made on embodiments of the
invention with reference to FIGS. 1 to 14.
FIG. 1 is an overall block diagram of a vehicle 100 such as an
electric vehicle (EV) in which a motor control device of a first
embodiment according to the invention is mounted. The vehicle
includes a power source unit 101 and a motor drive unit 102. The
power source unit 101 includes a battery 103, a cell controller 104
that monitors a battery state, and a relay circuit 105 that can
connect and disconnect an inverter 107 and the battery 103. In
addition, a battery controller 106 is included, for example, that
calculates a charging state (SOC; State of Charge) of the battery
as well as performs and interrupts power supply to the motor drive
unit 102.
As the battery 103, the battery that is formed of a battery pack
including plural secondary battery cells such as nickel hydrate
battery cells or lithium battery cells is used. In addition, the
plural secondary battery cells form a cell group in which several
to ten or more of the battery cells are connected in series, and
the battery, that is, the battery pack includes the several cell
groups that are connected in series or in series parallel.
Battery state data (such as inter-terminal voltage and a
temperature of the secondary battery cell) that is acquired in the
cell controller 104 is transmitted to the battery controller 106
via a communication path (represented by an arrow in FIG. 1). Based
on the received battery state data, the battery controller 106
calculates the SOC of the entire battery and that of the each
secondary battery and also calculates a DC power limit value from
the battery 103 to the motor drive unit 102 and the like.
Meanwhile, the motor drive unit 102 includes at least one inverter
107 and a motor 108. The inverter 107 is driven and controlled by a
signal from a motor controller 109 for driving and controlling the
motor 108. The motor controller 109 generates a drive signal for
the inverter 107 such that the motor is driven at a torque target
value or a rotation speed target value, for example, that is
received from an external controller 110 or the like via the
communication path or the like, and controls generated torque or a
rotation speed of the motor. Although a converter and the like are
not shown in the structure illustrated in FIG. 1, such equipment
may be provided.
FIG. 2 shows a detailed structure of a motor control computation
section in a motor control device (motor controller) 109 of the
embodiment according to the invention. The motor control device 109
includes a direct-current (DC) voltage detecting section 204 that
detects terminal voltage of a capacitor 203 from an output of a DC
voltage sensor 202, a motor rotation speed detecting section 207
that detects the motor rotation speed from an output of a motor
rotation sensor 205, and a motor current detecting section 209 that
detects a motor drive current from an output of a current sensor
208. Furthermore, a first current command calculating section 213
that calculates an output current in a d-q space on the basis of a
torque command value 210, a motor rotation speed detected value
211, and a DC voltage detected value 212, and a second current
command calculating section 216 that calculates the output current
in the d-q space that corresponds to the torque command value 210,
the motor rotation speed detected value 211, the DC voltage
detected value 212, and a battery current target value 215 are
included.
In addition, a current command switching section 218 is included
that switches between and outputs a current command value for
normal operation 214 that is an output value from the first current
command calculating section 213 and a current command value for
battery constant current operation 217 that is an output value from
the second current command calculating section 216 by a battery
constant current operation request signal 224. Furthermore, a
current control computing section 221 that outputs a current
control value 222 for controlling a three-phase output current to
the motor 108 on the basis of a current command value 219 output
from the current command switching section 218 and a current
detected value 220 output from the motor current detecting section,
and a PWM duty computing section 223 that determines a PWM duty on
the basis of the current control value 222 and that generates a
signal for driving the inverter 107 in the duty, are included. It
should be noted that voltage of the capacitor 203 is theoretically
the same as voltage of the battery 103.
Based on the torque command value 210 and the current motor
rotation speed detected value 211, the first current command
calculating section 213 determines a current command value at which
loss of the motor can be minimized within an adjustable range when
the motor 108 outputs the desired torque. In other words, in the
normal operation, the current command value for normal control 214
that is output from the first current command calculating section
213 is used to control the motor.
Meanwhile, based on the torque command value 210, the current motor
rotation speed detected value 211, the DC voltage detected value
212, and the battery current target value 215, the second current
command calculating section 216 determines a current command that
allows the motor 108 to output the desired torque and by which the
battery current reaches a target value.
(Principle of Constant Current Drive of the Motor)
A description will be made on constant current drive of the motor
in the motor control device according to the invention with
reference to FIG. 13.
(Normal Motor Operation)
FIG. 13 is a conceptual diagram for showing a curve for each
rotational torque in a condition that the rotational torque is
constant with respect to the motor current that is the three-phase
AC current (amplitude) supplied to a stator coil and a phase of the
current (electric angle) when the motor 108 is an IPM motor.
It should be noted that the rotation speed of the motor 108 is
constant in FIG. 13. As will be described later, there are a wide
variety of conditions for the constant rotation speed of the motor
108, that is, driving states at a constant speed of an electric
drive vehicle that is driven by the motor 108. In addition, because
the motor rotation speed and the required rotational torque are
varied according to a driving speed or a driving environment, the
state shown in FIG. 13 is merely one example. Furthermore, when the
vehicle is in a downhill travel, the motor 108 performs a
regenerative operation, and thus a drive state of the motor 108
such as that shown in FIG. 13 is not applied.
In the example shown in FIG. 13, the curve for certain constant
rotational torque has the lowest motor current value when a phase
.beta. (that is, the electric angle) of a drive current of the
stator coil (the motor current) is 40.degree. to 50.degree.. The
electric angle .beta. at which the motor current value becomes the
lowest is a maximum efficiency point of the motor 108, and in a
normal operation of the vehicle, the amplitude and the phase of the
motor current are controlled by controlling the inverter 107 to
change pulse width and the phase of the motor current such that the
motor 108 is operated at the maximum efficiency point.
For example, in the example of FIG. 13, when an uphill slope
gradually becomes steeper and the larger rotational torque is thus
required, the motor current and the electric angle are controlled
to be changed along a maximum efficiency line in the drawing.
(Constant Current Drive of the Battery in the Motor Control Device
According to the Invention)
FIG. 14 shows only one of the constant torque curves (.tau.=50
[Nm]) shown in FIG. 13 for ease of the description.
In the normal operation as described above, the motor controller
109 controls the inverter 107 such that the motor current and the
electric angle are located at the maximum efficiency point in the
drawing.
As will be described later, when it is determined that the vehicle
is in a constant speed traveling state, the motor 108 is shifted to
a state of the constant current drive.
A motor operation point moves from the maximum efficiency point in
FIG. 14 to a predetermined constant current operation point (will
be described later) along the constant torque curve on which
.tau.=50 [Nm]. The motor operation point is moved by changing the
motor current and the electric angle .beta. thereof. Due to the
constant torque state, the constant speed traveling of the vehicle
is maintained. Although the motor current and the electric angle
thereof can be changed linearly without following the constant
torque curve, this is not preferred due to occurrence of
acceleration/deceleration that is unintended by a driver.
Theoretically, the electric angle .beta. can be increased to near
90.degree.. However, as the electric angle approaches 90.degree.,
the motor current needs to be increased to generate the same
magnitude of torque, and the loss of the motor and the like are
increased, thereby lowering the efficiency as a result. In other
words, because the efficiency can be controlled without changing
the motor output, it is possible to control input power, that is,
the battery current.
It should be noted that the constant current operation can be
controlled in both a right side (.beta. increasing direction) and a
left side (.beta. decreasing direction) of the maximum efficiency
curve in FIG. 13; however, it is preferably controlled in the right
side of the maximum efficiency curve because a degree of the change
in the motor current that is caused by the change in the electric
angle .beta. is larger in the right side.
In addition, if the above operation is performed in both sides of
the maximum efficiency curve, the two electric angles .beta. are
available at the same motor current, and the operation thus becomes
unstable; therefore, such an operation is not performed.
It should be noted that, when the operation is returned from the
constant current operation to the normal operation at the maximum
efficiency point, the above procedure is performed in a reverse
order, and the motor current and the electric angle thereof are
changed from the constant current operation point along the
constant torque curve.
(A Method of Setting the Constant Current Operation Point)
A description will be made on an assumption that the constant
current operation is performed in the right side (.beta. increasing
direction) of the maximum efficiency curve that is shown in FIG. 13
as described above.
Theoretically, the electric angle .beta. can be increased to
90.degree.; however, the efficiency is lowered as the electric
angle approaches 90.degree.. The lowered efficiency results in heat
generation in the motor 108 and a temperature increase of the
motor; therefore, .beta. is changed within an appropriate range in
consideration of these issues. Furthermore, when the electric angle
.beta. approaches 90.degree., a higher motor current is required to
offset the lowered efficiency, and thus .beta. is changed in
consideration of whether or not the DC current (the battery
current) from the battery 103 to the inverter 107 can correspond to
the higher motor current.
When a value of the rotational torque is assumed at a certain
rotation speed, a minimum motor current value at which the motor
108 can output the torque (a value that corresponds to .beta. at
the maximum efficiency point) and a maximum motor current value
that is determined in consideration of the heat generation in the
motor 108 (corresponds to the maximum electric angle .beta.) are
each stored as a data table in a storage area of the motor
controller 109, for example.
As for the two current values that correspond to the motor rotation
speed and the torque in the normal operation at the maximum
efficiency point, the constant current operation as described above
is performed by using a motor current value located between the two
motor current values that respectively correspond to the electric
angle .beta. at the maximum efficiency point and the maximum
electric angle .beta. that is determined in consideration of the
heat generation and the output current of the battery in the above
example.
(A Method of Determining Whether or not the Constant Current
Operation is Possible)
A fluctuation range of .beta. in the constant speed traveling of
the vehicle, which is described above, can be obtained by actual
measurement during driving of the vehicle or by a simulation, and
the constant current operation can be performed if the fluctuation
range of .beta. is located between the above two motor current
values.
In the constant current operation in the actual vehicle, a
determination of whether or not the constant current operation can
be performed has to be made in consideration of an amount of the
dischargeable current of the battery 103 that is based on the
charging state (SOC) of the battery 103.
A description will hereinafter be made on a determination
method.
FIG. 3 shows examples of the data tables that are used by the
second current command calculating section 216. The second current
command calculating section 216 includes at least two current
command tables 301, 302 that correspond to the battery current and
two battery current tables 303, 304 as the data tables. The two
current command tables and the two battery current tables may be
tables that are based on the two motor current values (correspond
to .beta. at the maximum efficiency point and the maximum .beta.),
which are described above, for example, or may be based on values
at both ends of any portion between the two motor current
values.
The first current command table 301 is a current command table in
which the battery current is set to the minimum within the
adjustable range on the basis of the motor rotation speed (a range
from N0 to Nn) and a torque command (a range from T0 to Tn). For
example, when the current motor rotation speed is N1 and the torque
command is T1, an obtained current command is I*11x.
The second current command table 302 is a current command table in
which the battery current is set to the maximum within the
adjustable range on the basis of the motor rotation speed (the
range from N0 to Nn) and the torque command (the range from T0 to
Tn). For example, when the current motor rotation speed is N1 and
the torque command is T1, an obtained current command is I*11z. In
addition, the first battery current table 303 has the output
battery current that corresponds to the first current command table
301, and when the current motor rotation speed is N1 and the torque
command is T1 as described above, for example, an obtained battery
current value is IB11x.
The second battery current table 304 has the output battery current
that corresponds to the second current command table 302, and when
the current motor rotation speed is N1 and the torque command is T1
as described above, for example, an obtained battery current value
is IB11z.
A method of calculating the target battery current value IB* that
corresponds to the motor rotational speed N, the torque command T*,
and a target current command value (the motor current value) Idq*
by using the above table data will be described below.
First, the current command value that is extracted from the first
current command table 301 on the basis of the motor rotation speed
and the torque command is set as Idq1*, and the battery current
value at the same operation point that is extracted from the first
battery current table 303 is set as IB1. Next, the current command
value that is extracted from the second current command table 302
on the basis of the motor rotation speed and the torque command is
set as Idq2*, and the battery current value at the same operation
point that is extracted from the second battery current table 304
is set as IB2.
Here, because the current command value is Idq* when the target
battery current value is IB*, Idq* to be calculated establishes a
relationship as shown in FIG. 4 and can be calculated from a
following linear interpolation equation (1).
Idq*=(Idq2*-Idq1*)/(IB2-IB1).times.(IB*-IB1)+Idq1* (1)
Although linear relationships are established between the value in
the first current command table 301 and the value in the first
battery current table 303 and between the value in the second
current command table 302 and the value in the second battery
current table 304, as it can be understood from FIG. 13 and the
above description, the value in the first current command table 301
and the value in the second current command table 302 as well as
the values in the first battery current table 303 and the second
battery current table 304 are not strictly changed linearly.
However, because a change in the motor current value (the first
current command table 301 and the second current command table 302)
and a change in the battery current value (the first battery
current table 303 and the second battery current table 304)
establish a linear relationship, the target battery current value
IB* for the target current command value (the motor current value)
Idq* can be computed from the above equation (1) by using the above
equation.
It should be noted that, because battery voltage is actually
fluctuated at the same output, the battery current is also
fluctuated. Accordingly, the first and second battery current
tables are set according to reference battery voltage VBm, and the
target battery current value IB* may be converted by the reference
voltage value according to a current battery voltage VB^. The
converted target battery current value IB* is obtained from an
equation (2). IB*=IB*.times.(VBm/VB^) (2)
Although the current command tables are used in this embodiment, it
is considered that the same current command can be obtained by
another means.
As described above, it is possible in the above embodiment
according to the invention to select between a normal operation
mode in which the battery current fluctuates due to the fluctuation
of a motor load (the rotation speed, the torque) and a constant
current operation mode in which the battery current is maintained
to be constant within the predetermined adjustable range even with
the fluctuation of the motor load (the rotation speed, the
torque).
FIG. 5 is a flowchart for explaining a process of shifting to
processing by the motor controller 109 for controlling the motor
108 in either a battery constant current mode or a normal control
mode.
First, the torque command T*, the motor rotation speed N^, and the
target battery current value IB* are obtained (a step S501). Based
on these data, the first and second current command calculating
sections 213, 216 determine the current command values in the
normal operation mode and the constant current operation mode (a
step S502).
Next, it is determined whether or not battery constant current
operation permission has been received from the external controller
110 (a step S503). If it is determined to be in a battery constant
current operation permission state ("PERMITTED" in the step S503),
it is determined whether or not the battery current target value is
within a control range (a step S504). The battery constant current
operation permission will be described with reference to FIG. 7 and
later.
If it is determined to be controllable with the target battery
current ("TRUE" in the step S504), the current command value for
the battery constant current operation that is calculated in the
step S02 is selected (a step S505), a battery constant current
operation status is set to "TRUE" (a step S506), and the battery
constant current operation is initiated.
On the other hand, if the battery constant current operation
permission has not been received from the external controller 110
("PROHIBITED" in the step S503), or if it is determined that the
battery current target value is not within the control range
("FALSE" in the step S504), the current command value for the
normal current operation that is calculated in the step S502 is
selected (a step S507), the battery constant current operation
status is set to "FALSE" (a step S508), and the normal control
operation is initiated.
The battery constant current operation status set in the step S506
or the step S508 is sent to the battery controller 106 via the
communication path (a step S509).
FIG. 6 is a flowchart for explaining the details of the processing
in the step S504 of FIG. 5. The torque command T*, the motor
rotation speed NA, and the target battery current value IB* are
used, and the first battery current table 303 in FIG. 3 is referred
to so as to obtain the minimum battery current value IB1 (a step
S601). Next, the same torque command T*, the motor rotation speed
N^, and the target battery current value IB* are used, and the
second battery current table 304 in FIG. 3 is referred to so as to
obtain the maximum battery current value IB2 (a step S602).
If the target battery current value IB* is equal to the minimum
battery current value IB1 that is obtained in the step S601 or
larger and is equal to the maximum battery current value IB2 that
is obtained in the step S602 or smaller (YES in a step S603), a
battery constant current control range status is set to "TRUE" (a
step S604). On the other hand, if the target battery current value
IB* is smaller than the minimum battery current value IB1 that is
obtained in the step S601 or is larger than the maximum battery
current value IB2 that is obtained in the step S602 (NO in the step
S603), the battery constant current control range status is set to
"FALSE" (a step S605).
It should be noted that the minimum battery current value IB1 and
the maximum battery current value IB2 are respectively the minimum
current and the maximum current that the battery 103 can discharge.
Thus, the maximum battery current value IB2 is set to a value in
consideration with the charging state (SOC) of the battery 103.
After receiving the battery constant current operation status
(TRUE) from the motor controller 109, the battery controller 106
calculates the SOC.
FIG. 15 is a flowchart for explaining SOC computing processing that
is executed by the battery controller 106. It is determined in a
step S11 whether or not it is SOC calculation timing. If it is
determined to be the SOC calculation timing, a process proceeds to
a step S12. It is determined in the step S12 whether or not the
battery constant current operation status is "TRUE" (will be
described later in detail). If it is determined in the step S12
that the battery constant current operation status is "TRUE", CCV
measurement and SOC calculation are executed in a step S13. The CCV
measurement is executed by the cell controller 104 that is
controlled by the battery controller 106. If the steps S11 and S12
are negative, the step S13 is skipped.
It should be noted that information on whether or not it is the SOC
calculation timing and information of the battery constant current
operation status are sent from the external controller 110 that is
a host controller to the battery controller 106 together with a
command to execute an operation in FIG. 15, for example.
Various traveling states of the vehicle based on which the external
controller 110 determines whether or not the battery constant
current operation status is "TRUE" will hereinafter be described
with reference to FIG. 7 to FIG. 12.
FIG. 7 to FIG. 12 are flowcharts for explaining a first example to
a sixth example of the battery constant current operation
permission for which the motor control device of the embodiment
according to the invention can be used. In these cases, the vehicle
is mostly in the constant speed traveling state.
First Example
FIG. 7 is a flowchart for explaining the constant current operation
permission in the motor control device when a vehicle is in a
hill-hold travel.
The external controller 110 determines whether or not the vehicle
is currently in the hill-hold travel (a step S701). If it is
determined that the vehicle is in the bill-hold travel (YES in the
step S701), a battery constant current operation permission status
is set to "PERMITTED" (a step S703).
On the other hand, if the vehicle is not in the hill-hold travel
(NO in the step S701), the battery constant current operation
permission status is set to "PROHIBITED" (a step S702). The
external controller 110 transmits the battery constant current
operation status to the motor controller 109 and the battery
controller 106 (a step S704).
Second Example
FIG. 8 is a flowchart for explaining the constant current operation
permission in the motor control device when the vehicle is in a
hill-climb travel.
The external controller 110 determines whether or not the vehicle
is currently in the hill-climb travel (a step S801). If it is
determined that the vehicle is in the hill-climb travel (YES in the
step S801), the battery constant current operation permission
status is set to "PERMITTED" (a step S803).
On the other hand, when the vehicle is not in the hill-climb travel
(NO in the step S801), the battery constant current operation
permission status is set to "PROHIBITED" (a step S802). The
external controller 110 transmits the battery constant current
operation status to the motor controller 109 and the battery
controller 106 (a step S804).
Third Example
FIG. 9 is a flowchart for explaining the constant current operation
permission in the motor control device when the vehicle is in a
downhill travel. When the vehicle is in the downhill travel at the
constant speed, the motor 108 does not operate by receiving the AC
current from the inverter 107 but performs the regenerative
operation. However, due to the constant speed, a power generation
amount of the motor 108 is constant, and the DC current flowing
through the battery 103 is stabilized as in the constant current
operation of the motor 108; therefore, the CCV of the secondary
battery cell that forms the battery 103 can be measured
accurately.
The external controller 110 determines whether or not the vehicle
is currently in a downhill travel (a step S901). If it is
determined that the vehicle is in the downhill travel (YES in the
step S901), the battery constant current operation permission
status is set to "PERMITTED" (a step S903).
If the vehicle is not in the downhill travel (NO in the step S901),
the battery constant current operation permission status is set to
"PROHIBITED" (a step S902). The external controller 110 transmits
the battery constant current operation status to the motor
controller 109 and the battery controller 106 (a step S904).
Fourth Example
FIG. 10 is a flowchart for explaining the constant current
operation permission in the motor control device when the vehicle
is in a high-speed cruise travel.
The external controller 110 determines whether or not the vehicle
is currently in the high-speed cruise travel (a step SA01). If it
is determined that the vehicle is in the high-speed cruise travel
(YES in the step SA01), the battery constant current operation
permission status is set to "PERMITTED" (a step SA03).
On the other hand, if the vehicle is not in the high-speed cruise
travel (NO in the step SA01), the battery constant current
operation permission status is set to "PROHIBITED" (a step SA02).
The external controller 110 transmits the battery constant current
operation status to the motor controller 109 and the battery
controller 106 (a step SA04).
Fifth Example
FIG. 11 is a flowchart for explaining the constant current
operation permission in the motor control device when the vehicle
is in a reverse travel.
The external controller 110 determines whether or not the vehicle
is currently in the reverse travel (a step SB01). If it is
determined that the vehicle is in the reverse travel (YES in the
step SB01), the battery constant current operation permission
status is set to "PERMITTED" (a step SB03).
On the other hand, if the vehicle is not in the reverse travel (NO
in the step SB01), the battery constant current operation
permission status is set to "PROHIBITED" (a step SB02). The
external controller 110 transmits the battery constant current
operation status to the motor controller 109 and the battery
controller 106 (a step SB04).
Sixth Example
FIG. 12 is a flowchart for explaining a sixth example of the
constant current operation permission in the motor control device
according to the invention.
In this embodiment, processing in the first to fifth examples is
integrated. According to the processing, when any one of the
conditions described in the first to fifth examples is satisfied,
the battery constant current operation status is set to "PERMITTED"
(a step SC07).
On the other hand, when none of the conditions is satisfied, the
battery constant current operation status is set to "PROHIBITED" (a
step SC06). The external controller 110 transmits the battery
constant current operation status to the motor controller 109 and
the battery controller 106 (a step SC08).
In any of the examples, the battery controller 106 compares an SOC
calculation result when the battery current fluctuates with the SOC
calculation result during the battery constant current operation
and corrects the SOC calculation result.
It should be noted that the invention is not limited to the above
embodiments but includes various modifications. For example, the
above embodiments are described in detail for ease of understanding
but are not necessarily limited to the embodiments that encompass
the entire configuration described above. In addition, the
configuration of one embodiment can partially be replaced by the
configuration of another embodiment, and the configuration of
another embodiment can be added to the configuration of the one
embodiment. Furthermore, the configuration of each embodiment can
partially be removed, and the configuration of another embodiment
can partially be added to or replaced with the configuration of
each embodiment.
The configuration, functions, processing, and the like of the above
embodiments may partially or entirely be realized by hardware by
designing them in an integrated circuit, for example. The
configuration, functions, and the like of the above embodiments may
be realized by software, a program of which realizes each of the
functions and is interpreted and executed by a processor.
Information on a program, a table, and a file as components that
realize the above functions may be stored in a recording device
such as a memory, a hard disc, or a solid state drive (SSD) or in a
recording medium such as an IC card, an SD card, or a DVD. Control
lines and communication lines that are necessary for the
description are only shown, and all of the control lines and the
communication lines in a product are not necessarily shown. It can
be assumed that almost all of these components are actually
connected to each other.
Various embodiments and modifications have been described so far;
however, the invention is not limited thereto. Other aspects that
can be considered to fall within the scope of the technical idea of
the invention are also included in the scope of the invention.
The disclosure of the following priority application is
incorporated herein by reference in its entirety.
Japanese Patent Application No. 2011-209814 (filed on Sep. 26,
2011)
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